I wanted to comment on Ritz's journal (here:
http://www.livejournal.com/users/ritsu/8717.html), posting an interpretation about Kirito's Saisei no Asa... but lj refused my comment, because it was 5046 (or such) characters long, while comments have to be of 4300 characters max.! But I don't really see how I could make it shorter (you don't really have a global view of your post in these little comments-boxes...), so I'm sorry but this post actually is a comment to another user's post! Sorry for all this mess...
From now on, this is what was supposed to appear on Ritz's livejournal:
I don't know if he says that once he leaves the night he will be an adult (there's teenage before that), but... it's like he knows he acted as a child would ("I did what I did because I wanted to do it and that's it"), although from his words (and voice) you can definitely hear he's an adult speaking: there's a certain atmosphere of nostalgia, even though there's no regret. So... to me, it's more an adult justifying himself, because/knowing he's acting as a child (adults often do act like children in the end).
To interpret the song, I think you must keep in mind the first two lines:
"The vast earth, which has inevitably cracked, settles everything
The sun, which ruined our planned for harmony, was disappearing"
->"The earth" = the past, foundations for this past. But it cracked, which usually happens because of the sun (confirmed in the next sentence: it "ruined [...]"). So the sun is the reason for the bad feeling in the past, and somehow for the change: although it left, its consequences remain (...a cracked ground needs a lot of water (natural, I don't mean tears) before becoming green again!), which led to decisions: facing several possibilities, he chose the child-like option in the end.
Although, once again, he definitely says and expresses it as an adult would. Like when he says: "Children, whose mouths contain, don't know the fragments of a loved person": if I understand it well, it speaks of children who will speak no matter what, because they don't think that what they say will hurt people in front of them (which is a fact, indeed). So Kirito acts like a child because that's what he did, that's how he acted: he followed his own idea and point. Although the fact that he says it, and places it so early in the song, shows that he thought of other's reaction: an apology somehow, like saying: "that's the reason why I acted this way, sorry, I know that's what is good to me". So, contrary to a child, he tought of others' reaction: he only/mainly thought of himself here, and justifies it somehow.
That's why he wants to go on no matter what, even though the sun (=problem, at least the cause for the problem) left (cold morning the day after), because whatever happens will be a consequence to his own actions. + (Maybe) Even though it means he has to be lonely from now on: I don't know in Japanese, but in French you can say you feel "cold" when you are physically cold (no sun, no heat, such), but also when you're alone (no human warmth, somehow). So, speaking of a cold morning can be a way of speaking of a lonely morning, when you're on your own and point (and morning = beginning, this is traditionnal, in Japanese too I guess and probably English also) -> cold morning = a new beginning where he would be alone, on his own (= probably: "announcing it would probably mean that people would leave me, but it's fine, it would be better than the present situation anyway"). So it's another way to say: "sorry, I know I'm acting like a child here, but I'll face the consequences no matter what."
My only problems remains: "Incorrect thoughts in inflamed skin, if day breaks". I don't really get what you meant by "breaks"... "suddenly comes"? If you follow my interpretation of the rest of the song, I'd say it's like saying: "I know I act like a child here, but it's better than being burnt by you-know-what [the sun] made us be in this situation: it's better to see what the situation actually is right now [=during the evening], think about about what could be done and make decisions [=during the night], and see a new day come peacefully, even though maybe not happily [=the cold morning]". But well... I'm not sure I got this sentence correctly, so it's only an idea...
Anyway, if I got it correctly, Kirito seems to be trying to find a way to explain/somehow apologize for his selfishness. Because what he expresses here as "child acts" actually is selfishness: children don't realize it because they don't know enough about life yet, but Kirito does realize it, even when he writes this song. It's obvious in the words he uses and in the way he sings. That's why I also understand this song as a small apology, not in the meaning "I'm sorryyyyyy", but... "I did what I did, it's better for me, I act like a child [/am selfish] sometimes you know, hope I won't hurt you so much with that, but I know it's better for me, so... I'll face consequences no matter what, it's my decision after all".
And this song is so "lunar" (musically and lyrically) that, unless you ask Kirito himself, you will probably never know the definitive word about what this song actually means! You have my point of view anyway now...
Although it could be interesting if you translated "The Sun" if you have time too: it could prove I was totally wrong, and it would be fine, because there could be some relation to "the sun" he's referring to in Saisei no Asa, especially as both songs follow one another.
(-I shouldn't follow others' invitations to interpret Kirito's songs, because I really go into essays when I do, sorry I was so long, I only hope I wasn't completely wrong here, and that my interpretation was even a little interesting!)